Which personal pronoun is appropriate in single-author papers - 'I' or 'we'? Could the use of 'I' be considered egotistical? Or will the use of 'we' be considered to be grammatically incorrect?
It's field-dependent. English teachers told me the following:
In STEM you use "we" for "the reader and the author(s)", regardless of how many authors you have. (Note that the "royal we" would be the wrong term, since the authors don't wish to sound as ostentatious in "we, the king of ...".)
In languages, you use "I" if you are the sole author.